Jakarta , Indonesia -LRB- CNN -RRB- -- A crash involving two trains in central Indonesia Saturday killed 36 people and injured 26 , officials said .

The crash occurred when a train traveling from Semarang in Central Java to the capital of Jakarta was struck from behind by another train headed to Jakarta from Surabaya in East Java , according to Bambang Ervan , transport ministry spokesman .

Four coaches have been lifted off the track , and one remains , said Sugeng Priyono , spokesman for the Indonesian railway company .

Many people were crushed in the last carriage of the first train , which was stationary when the other train slammed into it , survivors said .

`` Suddenly I heard a very loud sound from behind , '' said Anwar Riksono , a passenger who was sleeping when the trains crashed . `` It shook so hard and the lights went off . ''

A crane lifted away large pieces of the train , mangled beyond recognition .

The transportation ministry says it is investigating whether the crash was caused by human or technical error .

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NEW : 36 people are dead and 26 are injured

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Indonesia 's transport ministry says one train struck another from behind

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Survivors say the first train was stationary when it was struck

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The cause of the crash is unclear